The present invention relates generally to improvements in a pneumatic cylinder, and more particularly, to a pneumatic cylinder, such as a rodless band cylinder having means for powering a secondary pneumatic unit secured to the reciprocally movable force transfer bracket associated with the cylinder.
Several types of pneumatic cylinders currently exist in the art, including, among possible others, cable cylinders and rodless or band cylinders. Although the features of the present invention may be applicable to any of these cylinders, it has particular application to rodless or rodless band cylinders of the type generally described in U.S. Pat. No. 4,545,290, the disclosure of which is incorporated herein by reference. Such a rodless cylinder includes an elongated cylinder member having an elongated, logitudinally extending slot, a piston reciprocally movable within the cylinder member, a sealing band or means for successively sealing the slot during reciprocal movement of the piston and a force transfer bracket for transferring the reciprocal movement of the piston to a workpiece outside of the cylinder. In some applications this force transfer bracket is connected directly to the desired workpiece in the form of a piston bracket, while in other applications the piston bracket is connected to a carrier bracket of the type described in pending U.S. application Ser. No. 810,403, filed Dec. 18, 1985, the disclosure of which is incorporated herein by reference. In this latter application, the workpiece is connected to the carrier bracket.
There are situations when it is desired to mount a second pneumatic unit, such as a secondary pneumatic cylinder, a pneumatic rotary actuator or some other pneumatic tool or device directly to the carrier bracket for reciprocal movement therewith. In such an application, this secondary pneumatic unit is normally designed for actuation either prior to, during or at the end of the stroke of the primary cylinder. A problem which exists with respect to this particular application is the difficulty in providing a source of air or other pneumatic pressure to this secondary pneumatic unit. Currently, when such an application is desired, hoses, tubes or other conduits are connected between a pneumatic power source and this secondary pneumatic unit to power the same. Such a structure, of course, can be quite cumbersome, complicated and expensive, particularly if the stroke of the primary cylinder is quite long. In such a case, the hoses or other conduits supplying the pneumatic power to the secondary pneumatic unit would have to be at least as long as the length of the primary cylinder and there would need to be means to take up the hose or conduit and to keep it from interfering with the rest of the operation during reciprocation of the secondary pneumatic unit along the stroke of the primary cylinder. While this is obviously less of a problem with primary cylinders of relatively short strokes, on the order of six inches to a foot, some of the primary cylinders can be twenty feet or longer.
Accordingly, there is a need in the art for an improved means for supplying pneumatic pressure to a secondary pneumatic unit connected to and movable with the reciprocating piston or carrier bracket of a pneumatic cylinder such as a rodless cylinder.